Bliskunov device for elongating long bones

ABSTRACT

This invention relates to medicine, in particular to surgical devices for curing the locomotor apparatus with the aid of osteosynthesis. In order to improve operational reliability during implantation, the structure of the inventive device for elongating long bones is embodied in such a way that the axes of the bearing part and the thread screwed part of a screw-holder are offset at a distance ranging from 0.5 to 0.8 mm. A boss (bulge) is embodied on the external body of the device on the side of the orifice in which said screw-holder is fixed. The specific structural embodiment of a finger makes it possible to reduce the traumatic effects of a surgical operation.

BACKGROUND OF THE INVENTION

This invention relates to medicine, namely to surgical devices forcuring the locomotor apparatus using osteosynthesis.

STATE OF THE ART

The known prior art of the invention is the long bone lengthening device(Ukrainian patent 34990A, 15.03.2001). The device contains an externalbody and an internal pullout hollow cylindrical body connected with eachother telescopically and equipped with a boss and a groove. The internalbody contains the through orifices for retention screws. The wall of theexternal body contains a threaded orifice with a screw-holder mounted init. The screw-holder consists of a bearing part with a transversethrough threaded orifice for a check screw and a thread screwed part,both parts coaxial. The device contains a ratchet-and-pawl connectedwith the external body and including a driving ratchet-wheel withratchet teeth, which contains a body, a driven teethed ratchet-wheelwith a body of its own, a retention ratchet-wheel, a lead screw which islocated inside the bodies, connected by means of a screw joint with theinternal pullout hollow body and is completed with a shank-end of afigured non-circular section for interaction with a similar figuredorifice located in the body of the driven ratchet-wheel, a thrust ringfor the lead screw connected monolithically with the external body, atelescopic rodded drive with a sphere, which contains a body and a rodand is capable of moving in the body, one side of which is connected bymeans of ears through the axis with a finger, on which a nut with astop, a washer and a lock-nut is screwed, while the other side isconnected through a swing joint's sphere with the driving ratchet-wheelof the ratchet-and-pawl, which in its turn is connected with theexternal body by means of a bayonet joint. The surface of the drivingratchet-wheel body is equipped with grooves, non-through in length anddepth, which lead onto the end surface. The driving ratchet-wheelcontains a bushing which has, on one side, end surface bosses to fitinto the grooves located in the body of the driving ratchet-wheel,elements of anchoring the bushing onto the body of the drivingratchet-wheel, and a spring located in the bushing, on the other side ofwhich there are end surface ratchet teeth. On one side the end surfaceof the body of the driven ratchet-wheel has ratchet teeth forinteraction with the ratchet teeth of the bushing of the drivingratchet-wheel, while on the other side of the surface of the body of thedriven ratchet-wheel there are grooves, non-through in length and depth,which lead out onto the end surface. The driven ratchet-wheel alsocontains a bushing, in which there are end surface bosses to fit intothe grooves of the driven ratchet-wheel body, elements of anchoring thebushing of the driven ratchet-wheel onto the driven ratchet-wheel body,and a spring located also in this bushing, on the other side of whichthere are also end surface ratchet teeth, whose direction is opposite tothat of the ratchet teeth of the driving ratchet-wheel's bushing. Theretention ratchet-wheel has the shape of a stop sleeve, which on one endsurface has ratchet teeth for interaction with the drivenratchet-wheel's bushing, while on the other end surface it has bosses tofit into the groove in the monolithic thrust ring of the external body.The boss of the external body is made in the shape of a hemiprismaticdowel, three lateral sides of which have flat surfaces, while on theexternal surface of the fourth lateral side, which fits into the innersurface of the external body, there are cylinder-shaped bossesmonolithic with the dowel and designed in such a way that they can beinserted into the through orifices in the external body. The height ofthe dowel's bosses corresponds to the thickness of the external bodywall. In the grooves of the ratchet-wheels' bodies there are additionalclosed contour hollows. The elements of anchoring the bushings of theratchet-wheels onto the bodies of the ratchet-wheels are joint pinsmounted in the orifices of the bosses. They are inserted into theadditional hollows of the grooves, with a possibility for the bushingsto move freely with respect to the bodies.

The closest prior art features similar to those of the device forelongating long bones by the present invention are as follows: theexternal body and the internal pullout cylindrical bodies, connectedtelescopically with each other, both bodies having the boss and thegroove, the through orifices in the internal bodies for the retentionscrews, the threaded orifice in the wall of the external body with ascrew-holder mounted in it, the screw-holder containing the bearing partand the thread screwed part, the ratchet-and-pawl connected with theexternal body and including the driving teethed ratchet-wheel whichcontains a body, the driven teethed ratchet-wheel which contains a body,the retention ratchet-wheel, the lead screw located inside the bodies,connected by means of a screw joint with the internal pullout hollowbody and equipped with the shank end of figured non-circular section forinteraction with the similar figured orifice made in the drivenratchet-wheel's body, the thrust ring for the lead screw, monolithicalwith the external body, the telescopic rodded drive with the sphere,which contains a body, and the rod made so that it can move inside thebody, which is connected on one side by means of ears through the axiswith the finger, while on the other side it is connected through thesphere of the swing joint with the driving ratchet-wheel of theratchet-and-pawl, which in its turn is connected with the external bodyby means of the bayonet joint, with the grooves, non-through in lengthand depth, made in the body of the driving ratchet-wheel and leading outonto the end surface. The driving ratchet-wheel contains the bushing,which has on the end surface the bosses to fit into the grooves in thebody of the driving ratchet-wheel, and the spring located in thebushing, on the other side of which there are the end surface ratchetteeth for interaction with the ratchet teeth of the drivingratchet-wheel. On the surface of the other side of the drivenratchet-wheel there are the grooves, non-through in length and depth,which lead out onto the end surface. The driven ratchet-wheel alsocontains the bushing, in which there are the end surface bosses to fitinto the grooves of the driven ratchet-wheel. Then there are theelements of anchoring the bushing of the driven ratchet-wheel onto thebody of the driven ratchet-wheel, and the spring located also in thisbushing, on the other side of which there are also the end surfaceratchet teeth, the direction of which being opposite to that of theratchet teeth of the driving ratchet-wheel's bushing. The retentionratchet-wheel has a shape of a stop sleeve, one end surface of which isequipped with the ratchet teeth for interaction with the bushing of thedriven ratchet-wheel and the other end surface has a boss to fit intothe groove made in the stop collar for the lead screw, which in its turnis made monolithically with the external body. The boss of the externalbody has the shape of a hemiprismatic dowel, three lateral sides ofwhich have flat surfaces, while on the outer surface of the fourthlateral side, which fits into the inner surface of the external body,there are the cylindrical bosses made monolithically with the dowel andso that they can be inserted into the through orifices on the externalbody. The height of the bosses of the dowel corresponds to the thicknessof the external body's wall. The grooves of the ratchet-wheels' bodiescontain the additional closed contour hollows, while the bosses of thebushings of the ratchet-wheels have the orifices. The elements ofanchoring the ratchet-wheels' bushings onto the ratchet-wheels' bodiesare the joint pins, which are mounted in the orifices of the bosses andinserted into the additional hollows of the grooves. The bushings canmove freely with respect to the bodies.

However, the above-mentioned device has the following shortcomings.

The mounting of the check screw into the transverse threaded orifice ofthe bearing part is necessary in order to prevent self-unscrewing of thescrew-holder under the influence of varying dynamic load which emergeswhen lengthening the limb. To mount the check screw it is necessary tomake channels on the front and rear surfaces of the trochanterian regionof the bone. The check screw can only be mounted with the help of aspecial conductor as the tool used for making a transverse orifice inthe bone penetrates at an angle to the curved surface, which may causetool deviation. All these actions require extra time during surgicaltreatment.

Therefore, three orifices located in the same plane are made on alimited area of the bone, which definitely weakens the bone in the saidsection.

A small thickness of the wall of the external body in the place wherethe threaded orifice is made, into which the screw-holder is to bemounted, does not provide a sufficient strength of the screw joint ofthe screw-holder and the external body.

During surgical treatment, the finger (having the structure by the priorart, i.e. a screwed-on nut equipped with a stop member, washer and alock-nut) is inserted into the through orifice in the iliac bone, whichis preceded by exfoliation of the soft tissues off the outer surface ofthe bone. To fix the finger the nut should be screwed up onto the innersurface of the iliac bone, which is preceded by exfoliation of the softtissues off the inner surface of the bone. Such exfoliation istraumatic. Besides, there exists a danger of injuring the peritoneum.

SUMMARY OF THE INVENTION

The problem of the present invention is to improve the device forelongating long bones wherein the constructive particularities providefor the improved reliability of functioning of the implanted device whenpower load is increased, as well as reducing the time of surgicaltreatment and decreasing the trauma rate when implanting the device.

This technical problem is solved as follows. The device for elongatinglong bones consists of the external body and the internal cylindricalpullout hollow bodies connected telescopically, which are equipped witha boss and a groove. The internal body has through orifices to fit intothe retention screws, while in the wall of the external body there is athreaded orifice with a screw-holder mounted into it. The screw-holdercontains the bearing part and the thread screwed part. Theratchet-and-pawl is connected with the external body and includes thedriving ratchet-wheel with the ratchet teeth, which contains a body,then there is a driven teethed ratchet-wheel, which contains a body, aretention ratchet-wheel, a lead screw located inside the bodies andconnected with the help of a screw joint with the internal pullouthollow body. It is also equipped with the shank end of figurednon-circular section for interaction with a similar figured orifice madein the body of the driven ratchet-wheel. Next, there is a thrust ringfor the lead screw made monolithically with the external body, atelescopic rodded drive with a sphere, which contains a body and a rodand which can move freely inside the body. On one side it is connectedwith the help of the ears through the axis with the finger, while on theother side it is connected through the sphere of the swing joint withthe driving ratchet-wheel of the ratchet-and-pawl, which in its turn isconnected with the external body by means of a bayonet joint. On thesurface of the body of the driving ratchet-wheel there are grooves,non-through in length and depth, which lead out onto the end surface.The driving ratchet-wheel contains a bushing, on one side of which thereare bosses to fit into the grooves made in the body of the drivingratchet-wheel, it further contains the elements of anchoring the bushingonto the body of the driving ratchet-wheel, and a spring located in thebushing, on the other side of which there are end surface ratchet teeth.On one side of the end surface of the body of the driven ratchet-wheelthere are ratchet teeth for interaction with the ratchet teeth of thedriving ratchet-wheel's bushing, while on the other side of the surfaceof the driven ratchet-wheel's body there are grooves, non-through inlength and depth, which lead out onto the end surface. The drivenratchet-wheel also contains a bushing, on one side of which there areend surface bosses to fit into the grooves of the body of the drivenratchet-wheel. Further there are the elements of anchoring the drivenratchet-wheel's bushing onto the driven ratchet-wheel's body, and aspring, which is also located in this bushing, on the other side ofwhich there are also end surface ratchet-teeth. The direction of theseratchet teeth is opposite to that of the ratchet teeth of the drivingratchet-wheel's bushing. The retention ratchet-wheel has a shape of astop sleeve, which is equipped on one end surface with the ratchet teethfor interaction with the bushing of the driven ratchet-wheel, while onthe other end surface it has bosses to fit into the groove made in thethrust ring for the lead screw, which is made monolithically with theexternal body. The boss of the external body has a shape of ahemiprismatic dowel, three lateral sides of which have flat surfaces,while on the outer surface of the fourth lateral side, which fits intothe inner surface of the external body, are located cylindrical bossesmade monolithically with the dowel, which can be inserted into thethrough orifices on the external body. The height of the bosses of thedowel corresponds to the thickness of the wall of the external body. Inthe grooves of the bodies of the ratchet-wheels there are someadditional closed contour hollows. And there are orifices in the bossesof the bushings of the ratchet-wheels. The elements of anchoring theratchet wheels' bushings to the ratchet-wheels' cases are joint pinsmounted into the bosses' orifices, which are inserted into theadditional hollows of the grooves with a possibility for the bushings tomove freely with respect to the bodies. By the invention, the axis ofthe threaded part is shifted with respect to the axis of the bearingpart of the screw-holder by 0.5-0.8 mm. On the external body, in theproximity to the threaded orifice, into which the screw-holder ismounted, there is a boss, while in the finger, which is connectedthrough the axis with the coupling rod, there is a clamp and an endsurface orifice, both located on the side of the rod. A plate for theears with a orifice for the axis is screwed into the orifice and anotherthrough threaded transverse orifice is made to fit into the lock screwof the crest of the iliac bone.

There exists the following cause-effect connection between the totalityof the essential features of the invention and the achieved technicalresult:

The 0.5-0.8 mm shift of the axes of the bearing part and the threadscrewed part of the screw-holder will provide a due self-locking of thelatter, which will permit to avoid unscrewing. If the shift is less than0.5 mm, it will not secure against unscrewing. If the shift is more than0.8 mm, it may cause difficulty in mounting and dismounting of thescrew-holder in the bone due to scarcity of space.

Making a boss (bulge) on the external body in the proximity to thethreaded orifice, into which the screw-holder is mounted, will providesufficient thickness of the body wall where the threaded orifice islocated. The medullary cavity in the upper, proximal part of the limbbone where the external body will be located has a physiologicaldilatation, which makes the boss admissible.

Using the structure of the finger connected through the axis with therod, made as an assembly, with a clamp and an end surface orifice, intowhich the plate for the ears with a orifice for the axis is screwed, andwith a through threaded transverse orifice for the blocking screw of thecrest of the iliac bone, will permit to lower the trauma rate ofsurgical treatment. The crest of the iliac bone is easily found in thecourse of palpation. In order to mount the blocking screw, it is merelyrequired to make a cut in the skin and drill a orifice in the crest.

The above-listed features improve the reliability of the functioning ofthe implanted device.

BRIEF DESCRIPTION OF THE FIGURES

The invention is illustrated with the graphic matter wherein:

FIG. 1—overall view of the device in section

FIG. 2—section A-A of FIG. 1

FIG. 3—section B-B of FIG. 1

FIG. 4—section C-C of FIG. 1

FIG. 5—fragment of driving ratchet-wheel

FIG. 6—hemiprismatic dowel

FIG. 7—view A of FIG. 6

FIG. 8—driven ratchet-wheel

FIG. 9—view B of FIG. 8

FIG. 10—retainer ratchet-wheel (stop sleeve)

FIG. 11—view C of FIG. 10

FIG. 12—device implantation diagram

THE DETAILED DESCRIPTION OF THE EMBODIMENT

The device consists of external body 1 with ratchet-and-pawl mounted init. The latter contains driving ratchet-wheel 2 in assembly, drivenratchet-wheel 3 in assembly, retainer ratchet-wheel 4 and pulloutinternal body 5. Sliding boss-groove joint between telescopic externalbody 1 and internal pullout body 5 is made so that hemiprismatic dowel(boss) 6 located on the inner wall of external body 1 interacts withgroove 7 of internal body 5. Driving ratchet-wheel 2 contains body 8connected on one side by means of swing joint 9 with telescopic roddeddrive 10 and bayonet joint 11—with external body 1, while on the otherside (see FIG. 5)—with spring 12, bushing 13 and two joint pins 14. Body8 has six grooves 15, non-through in length and depth, which areinserted into end surface 16 with six bosses 17 of bushing 13 insertedinto them with clearance fit (see FIG. 2). Besides, in two oppositegrooves 15 of body 8 there are additional closed contour hollows 18,into which joint pins 14 are inserted, so that bushing 13 can freelymove with respect to body 8 and which can be kept in assembly due topads (shoulders) 19 of body 8. On the side opposite to bosses 17 bushing13 has ratchet teeth 20 for interaction with teeth 21 of drivenratchet-wheel 3 (see FIG. 8). Driven ratchet-wheel 3 contains body 22,spring 23 and bushing 24 with two joint pins 25. On one side, body 22has ratchet teeth 21 and on the other side six grooves 26, whose designis similar to that of grooves 15 in body 8 of driving ratchet-wheel 2.Body 22 of driven ratchet-wheel 3 is connected with shank end 27 of leadscrew 28, which is also located inside bodies 1, 5 and 8 and bushings 4,13 and 24 in noncircular figured orifice 29. The structural design ofbushing 24 with two joint pins 25 is similar to the design of bushing13. It also has six bosses 30 inserted into grooves 26, while in twoopposite grooves 26 are also made additional hollows 31, where jointpins 25 are inserted. On the opposite side, bushing 24 has ratchet teeth32, which interact with teeth 33 of retainer ratchet-wheel 4 and havemutually opposite directions (see FIGS. 8, 9, 10, and 11). Retainerratchet-wheel 4 is made in the shape of a bushing which on one side hasratchet teeth 33, while on the other side there is boss 34 made so thatit can be inserted into groove 35 made in monolithic thrust ring 36 ofexternal body 1. Threaded part 37 of lead screw 28 has a screw jointwith threaded area 38 of internal body 5, whose length corresponds tothe estimated lengthening of the bone. FIG. 6 shows the hemiprismaticdowel 6, whose structure has got an essential advantage due to theincrease in number of its bosses 39, which permits to strengthen themechanical characteristics of dowel 6 without deteriorating theresistance of the wall of body 1 to power load. Mounting dowel 6 on theinside wall of body 1 will make it possible to encase it in closed spacebetween the wall of external body 1 and groove 7 of pullout internalbody 5, which helps to resolve the problem of its safe anchoring. Rod 40of rodded drive 10, which is made so that it can shift in body 41, isconnected with finger 43 through axis 42. Finger 43 is equipped withclamp 44 and end surface orifice with plate 45 for ears 46 screwed intoit. In finger 43 there is a through threaded transverse orifice forblocking screw 47 of the crest of the iliac bone. Rod 40 is connected bymeans of screw joint 48 with sphere 49 of swing joint 9. Body 1 is fixedonto proximal bone fragment 50 (see FIG. 12) using screw-holder 51equipped with threaded part 52 and bearing part 53. A 0.5-0.8 mm shiftof axes of threaded part 52 and bearing part 53 of screw-holder 51provides self-locking which prevents screw-holder 51 against unscrewing.Body 5 is fixed onto distal bone fragment 54 with retention screws 55and 56 inserted into the orifice of body 5. On the side of the threadedorifice on external body 1, into which screw-holder 51 is mounted, thereis boss (bulge) 57 to provide sufficient thickness of the wall of body1.

The ratchet-and-pawl of the device works as follows:

When driving ratchet-wheel 2 is turned counterclockwise (as seen fromwhere telescopic rodded drive 10 is) by the angular distance of theratchet-and-pawl, due to the linkage of teeth 20 and 21, drivenratchet-wheel 3 will be turning simultaneously, transmitting rotation tolead screw 28 through noncircular profiled joint 29 (see FIG. 3). Atthis point, bushing 24 acts as a locking device and its teeth 32 jumpover teeth 33 of stop sleeve 4.

When driving ratchet-wheel 2 is turned clockwise, an idle stroke isperformed, with teeth 20 of bushing 13, which at this point acts as aratchet, jumping over teeth 21 of body 22 of driven ratchet-wheel 3. Atthis point stop sleeve 4, whose teeth 33 will be interacting with teeth32 of bushing 24, will not let driven ratchet-wheel 3 make a turn. Atsuch a pattern of interaction of the components of the ratchet-and-pawl,the power load acting on the device will not in any way affect thereliability of its functioning.

The advantage of the structure of dowel 6 (see FIGS. 6 and 7) lies inthe fact that due to the increase in the number of bosses 39 it ispossible to calculate its requisite mechanical characteristics withoutweakening the resistance of the wall of body 1 to power load. Mountingdowel 6 on the inside wall of body 1 makes it possible to locate it inclosed space between the wall of external body 1 and groove 7 ofinternal body 5, which helps to resolve the problem of its reliableanchoring.

During surgical treatment the patient is laid on his/her side so thatthe limb to be operated on should be bent in the knee and hip joints.Cuts in the soft tissues are made over the greater trochanter and overthe upper flaring portion of the iliac bone. Using a drill, whosediameter corresponds to the outer diameter of body 1, a channel in themedullary cavity of the femur is drilled through the greater trochanterto the depth required for mounting of the entire device. Next comesosteotomy (bone cutting), which is done by any known way, which helpsget two bone fragments: proximal 50 and distal 54. Fragment 54 is fixedonto internal body 5 using screws 55 and 56, while in fragment 50mutually two perpendicular orifices for screws 51 and 52 are drilled.The device is placed inside the femur, screw 51 is screwed into body 1through the cortical layer of the femur. Next, the telescopic roddeddrive is introduced through the greater and medium sciatic muscles, atransverse orifice is drilled in the wing of the iliac bone, and finger43, equipped with clamp 44 and end surface orifice with plate 45 forears 46 screwed into it, is inserted into this transverse orifice.Through axis 42 finger 43 is connected with body 42. A cut is done onthe skin over the crest of the iliac bone, and a orifice coaxial withthe transverse orifice in finger 43, through which it is fixed by meansof blocking screw 47, is drilled in the bone. The wounds are thensutured. During the postoperative period, after removal of stitches thepatient is asked to turn his/her leg around the long axis of the hipfirst inwards then outwards. The number of teeth in ratchet-wheels 2 and3 and in bushing 4 is 18 each, while the actuation (functioning) anglemakes up 20°.

When turning the hip inwards (working stroke) telescopic rodded drive 10returns driving ratchet-wheel 2 through swing joint 9 back to theactuation angle and through teeth 20 of its bushing 13 transmits thetorque on tooth 21 to body 22 of driven ratchet-wheel 3. Drivenratchet-wheel 3 further transmits the torque onto lead screw 28 throughthe joint of noncircular figured shank end 27 and orifice 29. At thispoint, teeth 32 of bushing 24 of driven ratchet-wheel 3, acting as aspring loaded ratchet, jump over the teeth of retainer ratchet-wheel 4.

When turning the hip outwards (idle stroke) the formed power circuit(lead screw 28, pullout body 5, retainer wheel 4, driven ratchet-wheel3) fixes body 22 of driven ratchet-wheel 3 against the axis shift withrespect to shank end 27 of lead screw 28, while teeth 20 of bushing 13of driving ratchet-wheel 2 jump over teeth 21 of body 22 of drivenratchet-wheel 3, which makes bushing 13 interlock for the next workingstroke. At a such kinematic pattern of the ratchet-and-pawl, the body ofdriven ratchet-wheel 22 is kept permanently fixed against the axialshift by forces of friction, both during the working and idle strokes ofthe ratchet-and-pawl. The functions of shifting are performed bybushings 13 and 24 mounted outside the zone of action of the powercircuit.

The number of couples of turns within 24 hours is chosen depending onthe lengthening rate and the step angle of threaded part 37 of leadscrew 28. At a 1 mm per 24 hrs lengthening rate and a 1 mm step angle ofthe threading 18 couples of turns are required within 24 hours. Afterachievement of the estimated lengthening, e.g. 10 cm, which correspondsto the length of threaded area 38 of body 5, telescopic rodded drive 10can be removed. For this purpose, a 2-3 cm cut is done in the region ofthe wing of the iliac bone, connections of finger 43 of telescopicrodded drive 10 with blocking screw 47 and plate 45 are disconnected androd 40 with sphere 49 is unscrewed. After maturing of the distractionregenerate (i.e. when the density of the callus formed as a result ofthe bone lengthening equals the density of the bone) the device is to beremoved out of the bone as an ordinary intraosseous retainer, for whichpurpose retention screws 51, 52, 55 and 56 are removed and a cut in theregion of the greater trochanter is done.

1. A device for elongating long bones comprising an external and apullout internal cylindrical hollow body, connected telescopically, eachhaving a boss and a groove, said internal body having through orificesfor retention screws, a wall of said external body having a threadedorifice with a screw-holder mounted therein, said screw-holdercontaining a coaxial bearing part and a thread screwed part, aratchet-and-pawl gear connected with said external body, a lead screwdisposed inside said external body, which is connected by way of a screwjoint with the internal pullout hollow body, said ratchet-and-pawl gearbeing further connected with said lead screw, and having a thrust ringfor said lead screw operable to pull out said internal body relative tosaid external body, a telescopic rodded drive, with a sphere, said roddrive operable to transmit rotational movement, connected to a drivingratchet wheel by means of a swing joint and to the external body bymeans of a bayonet joint, said driving ratchet wheel connected to saidlead screw, a key in communication with said external body and saidinternal body for preventing rotational shifting of the external bodyrelative to said internal body, wherein an axis of said thread screwedpart of the screw-holder is shifted relative to an axis of said bearingpart by 0.5-0.8 mm, the external body in said threaded orifice area,where said screw-holder is mounted, having a boss for strengthening saidexternal body, and a finger connected through an axis of said rod,having, from a side of said rod, a clamp and an end surface orifice, inwhich a plate for ears with an orifice for the axis is mounted, and athrough threaded transverse orifice for a blocking screw of the crest ofthe iliac bone.
 2. A device for elongating long bones comprising anexternal and a pullout internal cylindrical hollow body, connectedtelescopically, each having a boss and a groove, said internal bodyhaving through orifices for retention screws, a wall of said externalbody having a threaded orifice with a screw-holder mounted therein, saidscrew-holder containing a coaxial bearing part and a thread screwedpart, a ratchet-and-pawl gear connected with said external body, a leadscrew disposed inside said external body, which is connected by way of ascrew joint with the internal pullout hollow body, said ratchet-and-pawlgear being further connected with said lead screw, and having a thrustring for said lead screw operable to pull out said internal bodyrelative to said external body, a telescopic rodded drive, with asphere, said rod drive operable to transmit rotational movement,connected to a driving ratchet wheel by means of a swing joint and tothe external body by means of a bayonet joint, said driving ratchetwheel connected to said lead screw, a key in communication with saidexternal body and said internal body for preventing rotational shiftingof the external body relative to said internal body, wherein an axis ofsaid thread screwed part of the screw-holder is shifted relative to anaxis of said bearing part by 0.5-0.8 mm, the external body in saidthreaded orifice area, where said screw-holder is mounted, having a bossfor strengthening said external body, and a finger connected proximallythrough an axis perpendicular to the longitudinal axis of said rod, saidfinger having, a clamp and an end surface orifice with plate distallyconnecting said finger to an ear of said rod drive, and said fingerhaving distally a through threaded transverse orifice for a blockingscrew of the crest of the iliac bone.